饥饿对南方鲇幼鱼游泳能力个体变异和重复性的影响

摘要

In this study, we used the juvenile southern catfish (Silurus meridionalis Chen) as the experimental model to investigate effects of food deprivation on individual variation and repeatability of both aerobic and anaerobic swimming performance in carnivorous fish. The critical swimming speed (Ucrit), constant acceleration speed (Ucat), and the endu-rance of both the control group (n=28) and fasting group (n=29) were measured before and after fasting under (25 ± 0.5)℃. Our results showed that the body mass, body length and condition factor of the fasting group decreased significantly by (15.10±0.86)%, (2.57±0.40)%and (7.94±1.59)%after the fasting treatment (P<0.05), respectively. In the contrast, these morphological parameters of the control group did not change after the fasting treatment. In terms of swimming per-formance, the control group showed no difference in Ucat and endurance, but the Ucrit declined significantly by (6.63±2.25)%(P=0.031) after the fasting treatment. Unlike the control group, the fasting group showed remarkable de-crease in Ucrit and Ucat by (26.00±2.76)% and (13.68±1.86)% (P<0.001) respectively, without change in the endurance. The decreased proportion of the Ucrit was greatly larger than that of the Ucat (P<0.001) in the fasting group. The coeffi-cient of variation (CV) of the endurance, Ucrit and Ucat of the fasting group uniformly increased after the fasting treatment, whereas the CVs of the control group changed both positively and negatively. A significant positive correlation between Ucrit and Ucat of the S. meridionalis was observed in either control or fasting group, and two-week food deprivation did not affect this correlation. This implied that there was no potential trade-off between aerobic and anaerobic locomotion ability in individual southern catfish. The present study suggested that fasting profoundly decreased aerobic and an-aerobic swimming performance in juvenile southern catfish, but increased the CV of their swimming performance. The correlation between aerobic and anaerobic swimming ability maintained stable during food deprivation. The physio-logical traits of anaerobic swimming may be relatively conservative in the environment compared to aerobic swimming. The shift in the large variation of individual performance may reflect divergent natural selection favoring alternative strategies for foraging and predation.%为考察肉食性鱼类有氧和无氧运动能力的种内个体变异、重复性及其对饥饿的响应,研究以南方鲇(Silurus meridionalis Chen)幼鱼为实验对象,在(25±0.5)℃条件下测定对照组(n=28)和饥饿组(n=29)的临界游泳速度(Critical swimming speed, Ucrit)、暴发游泳速度(Constant acceleration speed, Ucat)和固定流速耐受时间(Endurance),分析游泳能力的个体变异、稳定性及饥饿的影响。结果显示：(1)饥饿组的体重、体长和肥满度均分别显著下降了(15.10±0.86)%、(2.57±0.40)%和(7.94±1.59)%(P<0.05),而对照组无明显变化；(2)对照组的Ucat和耐受时间无明显变化(P>0.05),但 Ucrit下降(6.63±2.25)%(P=0.031),而除耐受时间外饥饿组其 Ucrit和Ucat 分别显著下降了(26.00±2.76)%和(13.68±1.86)%(P<0.001),并饥饿组 Ucrit 的下降比例显著大于其Ucat(P<0.001)；(3)并且对照组三个指标的变异系数(Coefficient of variation, CV)变化方向和程度不尽相同,饥饿组的Ucrit、Ucat和耐受时间的CV全部增加；(4)南方鲇幼鱼Ucrit和Ucat呈正相关且2周的饥饿并未改变此正相关。饥饿明显降低南方鲇幼鱼两种游泳能力并导致游泳能力的个体变异变大,但没有改变该种鱼的有氧运动能力和无氧运动能力之间的内在正相关关系。研究表明无氧运动能力在环境改变后显得更为保守,种内个体变异的变动可能有利于在相同自然选择压力下种内个体采取不同的捕食和避敌对策。